silverbullet/web/cm_plugins/fenced_code.ts

import { panelHtml } from "../components/panel.tsx";
import { Decoration, EditorState, syntaxTree, WidgetType } from "../deps.ts";
import type { Editor } from "../editor.tsx";
import { CodeWidgetCallback } from "../hooks/code_widget.ts";
import {
  decoratorStateField,
  invisibleDecoration,
  isCursorInRange,
} from "./util.ts";

class IFrameWidget extends WidgetType {
  constructor(
    readonly from: number,
    readonly to: number,
    readonly editor: Editor,
    readonly bodyText: string,
    readonly codeWidgetCallback: CodeWidgetCallback,
  ) {
    super();
  }

  toDOM(): HTMLElement {
    const iframe = document.createElement("iframe");
    iframe.srcdoc = panelHtml;
    // iframe.style.height = "0";

    const messageListener = (evt: any) => {
      if (evt.source !== iframe.contentWindow) {
        return;
      }
      const data = evt.data;
      if (!data) {
        return;
      }
      switch (data.type) {
        case "event":
          this.editor.dispatchAppEvent(data.name, ...data.args);
          break;
        case "setHeight":
          iframe.style.height = data.height + "px";
          break;
        case "setBody":
          this.editor.editorView!.dispatch({
            changes: {
              from: this.from,
              to: this.to,
              insert: data.body,
            },
          });
          break;
        case "blur":
          this.editor.editorView!.dispatch({
            selection: { anchor: this.from },
          });
          this.editor.focus();
          break;
      }
    };

    iframe.onload = () => {
      // Subscribe to message event on global object (to receive messages from iframe)
      globalThis.addEventListener("message", messageListener);
      this.codeWidgetCallback(this.bodyText).then(({ html, script }) => {
        iframe.contentWindow!.postMessage({
          type: "html",
          html,
          script,
        });
        iframe.contentWindow!.onunload = () => {
          // Unsubscribing from events
          globalThis.removeEventListener("message", messageListener);
        };
      });
    };
    return iframe;
  }

  eq(other: WidgetType): boolean {
    return (
      other instanceof IFrameWidget &&
      other.bodyText === this.bodyText
    );
  }
}

export function fencedCodePlugin(editor: Editor) {
  return decoratorStateField((state: EditorState) => {
    const widgets: any[] = [];
    syntaxTree(state).iterate({
      enter({ from, to, name, node }) {
        if (name === "FencedCode") {
          if (isCursorInRange(state, [from, to])) return;
          const text = state.sliceDoc(from, to);
          const [_, lang] = text.match(/^```(\w+)?/)!;
          const codeWidgetCallback = editor.codeWidgetHook.codeWidgetCallbacks
            .get(lang);
          if (codeWidgetCallback) {
            // We got a custom renderer!
            const lineStrings = text.split("\n");

            const lines: { from: number; to: number }[] = [];
            let fromIt = from;
            for (const line of lineStrings) {
              lines.push({
                from: fromIt,
                to: fromIt + line.length,
              });
              fromIt += line.length + 1;
            }

            const firstLine = lines[0], lastLine = lines[lines.length - 1];

            // In case of doubt, back out
            if (!firstLine || !lastLine) return;

            widgets.push(
              invisibleDecoration.range(firstLine.from, firstLine.to),
            );
            widgets.push(
              invisibleDecoration.range(lastLine.from, lastLine.to),
            );
            widgets.push(
              Decoration.line({
                class: "sb-fenced-code-iframe",
              }).range(firstLine.from),
            );
            widgets.push(
              Decoration.line({
                class: "sb-fenced-code-hide",
              }).range(lastLine.from),
            );

            lines.slice(1, lines.length - 1).forEach((line) => {
              widgets.push(
                Decoration.line({ class: "sb-line-table-outside" }).range(
                  line.from,
                ),
              );
            });

            widgets.push(
              Decoration.widget({
                widget: new IFrameWidget(
                  from + lineStrings[0].length + 1,
                  to - lineStrings[lineStrings.length - 1].length - 1,
                  editor,
                  lineStrings.slice(1, lineStrings.length - 1).join("\n"),
                  codeWidgetCallback,
                ),
              }).range(from),
            );
            return false;
          }
          return true;
        }
        if (
          name === "CodeMark"
        ) {
          const parent = node.parent!;
          // Hide ONLY if CodeMark is not insine backticks (InlineCode) and the cursor is placed outside
          if (
            parent.node.name !== "InlineCode" &&
            !isCursorInRange(state, [parent.from, parent.to])
          ) {
            widgets.push(
              Decoration.line({
                class: "sb-line-code-outside",
              }).range(state.doc.lineAt(from).from),
            );
          }
        }
      },
    });
    return Decoration.set(widgets, true);
  });
}